The aim of the studies is the identification and purification of the nephritogenic antigen in streptococci. It is also the aim to devise a simple test to detect the presence of antibodies against the nephritogenic factor in healthy individuals of all ages and in patients with renal diseases. The final aim is the development of a vaccine against poststreptococcal glomerulonephritis. Another aim is the follow up of patients involved in sporadic and epidemic outbreaks of poststreptococcal glomerulonephritis as to immunologic and clinical sequelae, the means of recognizing continued immunologic activity and the percentage ending in endstage kidneys. Morbidity and mortality will be followed in a large group of patients with Systemic Lupus Erythemtosus treated with very high dose steroid therapy governed exclusively by immunologic guideposts.